This invention relates to a filter with a filter element for screening the oil of an internal combustion engine and, more specifically, to a filter in which valve means control the flow of oil between the inlet and outlet of the filter.
Most prior filters of the type with which the invention is concerned have two separate valves. One valve is a flow control valve which causes the oil to enter the filter at one location and discharge from another location after flowing through the filter element and which holds oil in the filter when the engine is shut down. The second valve is a pressure relief valve which, under certain conditions, causes the flow to bypass the filter element altogether and to pass directly from the inlet to the outlet of the filter.
While most commercially available filters utilize separate flow control and pressure relief valves, there are filters in which the valve functions are combined into a unitary structure. Typical of a filter with a multiple function valve is that disclosed in Thornton et al U.S. Pat. 3,567,022. The multiple function valve structure of the Thornton et al patent, however, is relatively complex and is comparatively expensive to manufacture and assemble.